This invention relates to pneumatic tires and, more particularly, to pneumatic tires of the radial type the carcass reinforcement of which has additional plies.
A so-called radial tire has a tread reinforcement comprising at least two crossed plies of cords, preferably of metal, which are oblique with respect to the longitudinal direction of the tire. Such a tire also has a carcass reinforcement comprising at least one ply of substantially radial cords or cables that are continuous from one bead wire to the other.
Tires of this type have the reputation of providing a comfortable ride due to the flexibility of their carcass reinforcement. However, precisely because of the great flexibility of the carcass reinforcement, the stiffness of the tread reinforcement is not sufficient to obtain the best highway behavior under all circumstances.
For this reason it has been attempted to correct the drawbacks resulting from the flexibility of the carcass reinforcement. However, the means of correction employed heretofore have decreased the comfort of the ride.
For example, oblique auxiliary plies, that is to say plies independent of the carcass ply proper and of a width less than one-half the width of the carcass reinforcement, measured from bead wire to bead wire, have been added to the carcass reinforcement. The corrective action of the auxiliary plies depends to a great extent on their width. As this width reduces the width of the zones in which the carcass reinforcement has substantially radial cords, the auxiliary plies necessarily reduce the comfort of the ride.